libpod/image: Use ParseNormalizedNamed in RepoDigests

Avoid generating
quay.io/openshift-release-dev/ocp-release@sha256@sha256:239... and
similar when the image name is already digest-based [1].  It's not
clear exactly how we get into this state, but as shown by the unit
tests, the new code handles this case correctly (while the previous
code does not).

[1]: https://github.com/containers/libpod/issues/2086

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #2106
Approved by: rhatdan

1 files changed, 15 insertions, 3 deletions

diff --git a/libpod/image/image.go b/libpod/image/image.go
index 3a6d0e305..2e12adb70 100644
--- a/libpod/image/image.go
+++ b/libpod/image/image.go
@@ -305,12 +305,24 @@ func (i *Image) Names() []string {
 }
 
 // RepoDigests returns a string array of repodigests associated with the image
-func (i *Image) RepoDigests() []string {
+func (i *Image) RepoDigests() ([]string, error) {
 	var repoDigests []string
+	digest := i.Digest()
+
 	for _, name := range i.Names() {
-		repoDigests = append(repoDigests, strings.SplitN(name, ":", 2)[0]+"@"+i.Digest().String())
+		named, err := reference.ParseNormalizedNamed(name)
+		if err != nil {
+			return nil, err
+		}
+
+		canonical, err := reference.WithDigest(reference.TrimNamed(named), digest)
+		if err != nil {
+			return nil, err
+		}
+
+		repoDigests = append(repoDigests, canonical.String())
 	}
-	return repoDigests
+	return repoDigests, nil
 }
 
 // Created returns the time the image was created